The present disclosure relates to a micropillar array, and a system and method for manufacturing a micropillar array.
In a world with growing demand for electrical power, 3D batteries are an emerging hot topic. Solid state thin-film batteries deposited on three dimensional (3D) micropatterned structures have the potential to combine high power density and high energy density. The specific surface area of the microstructures enable high currents to be drawn from the battery and also allows quick charging. Furthermore, the densely packed microstructures enable relatively high volumetric energy storage. Pillar structures are preferred due to the easy accessibility of their entire surface when compared to porous or perforated structures of similar aspect ratio and dimensions.
Various methods are proposed in the literature to make high-aspect nanowires or nanopillars on a substrate for battery electrode applications. See for example patent literature US2009214956 AA, WO11094642 A1, US2007059584 AA, US2006216603 AA, US2012094192 AA. The structures are either made of a metal or of doped silicon. For example, the methods may comprises deposition of the nanowire material inside a nanoporous template (e.g. electrochemically etched silicon or anodized aluminum), and the subsequent dissolution of template in order to release the nanowires. The produced nanowires may have a variety of sizes ranging from a hundred nanometer to a few microns, and various heights ranging from a few microns to hundreds of microns.
Unfortunately, techniques involving electrodeposited metal nanowires, are typically not able to produce wires with sufficient height (in the range of hundreds of microns), since the wires may tend to fall over. Furthermore, high aspect ratio structures in the nanometer scale may hold relatively less charge capacity per unit volume than micrometer scale structures. Furthermore, using a molding technique (e.g. US2012183732A1) may be impractical. Furthermore, producing micropillars by deep reactive ion etching in a silicon wafer may not be economically viable. Indeed, to improve the cost-effectivity, it is desired that the structures be processed on relatively cheap substrates (e.g. metal foils) with a cheap large-area process.
Accordingly, there remains a desire for improved systems, methods, and products providing economically-viable high-aspect ratio conductive micropillar structures, e.g. for use in 3D batteries and other applications.